1. Field of the Invention
The present invention relates to cellular telecommunications, particularly to a method, system, and corresponding Packet Data Serving Node (PDSN) for performing Mobile IP (MIP) registrations.
2. Description of the Related Art
The Code Division Multiple Access 2000 (CDMA2000) cellular telecommunications network is one of the third generation (3G) for the IP-based (Internet Protocol—based) cellular telecommunications networks, that can provide high-speed wireless connections allowing for multimedia sessions over wireless interfaces. In such an IP-based cellular telecommunications network, including in the CDMA 2000 cellular telecommunications network, for a Mobile Node (MN) to be able to carry out a wireless communications, a Packet Control Function (PCF) of a Base Station (BS) serving the MN must first establish a Radio network Packet data serving node (RP) session with a Packet Data Serving Node (PDSN). The establishment of the RP session is followed by the starting of a point-to-point protocol (PPP) connection, or session, between the MN and the PDSN, which is in turn followed by the MN's Mobile IP (Mobile Internet Protocol or MIP) registration with the PDSN. An MIP registration request is thus passed from the MN to the PDSN over the PPP connection and via the PCF, which forwards it to the PDSN over the RP session. The purpose of the Mobile IP registration signaling is to allow the MN to obtain an IP address for identifying the MN during the communications over the PPP connection.
In some instances, the MIP registration of the MN with the network may be unsuccessful, due to various reasons, such as for example invalid challenge value or time based desynchronization between the MN and the PDSN, etc. The cellular telecommunications standard IS-835 for CDMA 2000 defines that the RP and PPP sessions must most often be terminated in cases wherein an MIP registration is unsuccessful or rejected. However, for some conditions wherein the MN can correct the error that led to the unsuccessful MIP registration, the sessions may be kept.
Given the unpredictable behavior of MNs in various operational situations, the scenarios defined by the standard and specifying when the PPP sessions should be terminated are not consistent, as are the scenarios wherein according to the standard the sessions can be kept alive. For example, it was observed that in many situations the RP and PPP sessions are kept alive for long periods of time (default value is typically set to at least 9000 seconds in many implementations) in instances wherein, for various reasons, the MN does not correct the encountered internal error(s) and therefore does not attempt an additional MIP registration as expected. In other instances it was observed that the sessions were terminated while the MN was retrying an additional MIP registration leading to the reestablishment of the RP and PPP sessions immediately after their termination.
Therefore, due substantially to the unpredictable behavior the MNs may have in operational situations that were not tested and thus discovered, and for which no adequate solutions were implemented beforehand, many cases arise wherein the handling (keeping alive or killing) of the RP and PPP connections is inadequate.
It would be advantageous to have a consistent method allowing for repetitive MIP registration attempts in case of initial MIP registration failure for all the possible scenarios and situations that will occur in operational situations.
In particular, there is an advantage to have a method, a system, and a PDSN that could maintain the RP and PPP connections alive for a predetermined amount of time following an MIP registration failure for allowing subsequent MIP registration attempts to be performed.